Fuel injection system



Nov. 14, 1967 G. D. woLFF 3,352,245

FUEL INJECTION SYSTEM Filed Dec. 9, 1965 United States Patent O 3,352,245 FUEL INJECTION SYSTEM George D. Wolff, Hazel Crest, Ill., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Filed Dec. 9, 1965, Ser. No. 521,237 15 Claims. (Cl. 103--2) This invention relates to means for regulating the temperature of fuel injectors of internal combustion engines employing solid injection of fuel.

Heretofore the seat areas of injection nozzles have lost hardness due to high engine temperatures developed at the injectors. This problm becomes increasingly serious in engines with high thermal loads such as supercharged engines. Also, it has been shown that during idle operation of an engine, acid corrosion of the injector parts may occur when these parts are below about 40 degrees centigrade. During combustion sulphur trioXide (S03) is formed and `condenses on the cooler steel parts of the injector forming sulphuric acid which corrodes the surfaces of the injector parts.

It is an object of this invention to provide a fuel injection system employing a distributor type fuel injection pump and pressure operated injection nozzles wherein the nozzles are cooled by fuel flow from a supply pump to the injection pump.

It is a further object of this invention to provide a fuel injection system as outlined in previous object wherein thermostatic or temperature responsive means are employed to substantially prevent cooling fuel flow until the injector temperature is above a predetermined minimum.

It is a further object of this invention to provide injector cooling in a fuel injection system having a precharged fuel injection pump, that is an injection pump wherein the injector lines are precharged at an intermediate supply pressure during noninjection intervals.

It is a further object of this invention to provide a fuel injection system wherein the nozzles are not only cooled by fuel ow therethrough during noninjection intervals but also for a predetermined time following engine shutdown.

These and other objects and advantages will be apparent when the following description is read in conjunction with the drawings, in which:

FIG. 1 is a partially schematic showing of one embodiment of my invention;

FIG. 2 is a section view taken along line II-II in FIG. l;

FIG. 3 is a section view of an outward opening nozzle with diaphragm check valve means;

FIG. 4 is a partially schematic showing of a second embodiment of my invention; and

FIGURE 5 is a schematic showing of an alternate embodiment of the present invention wherein an overriding clutch drive means is employed.

Referring to FIGS. l and 2 the precharged fuel injection pump 11 is similar to the injection pump shown in -my copending U.S. patent application Ser. No. 405,189, filed Oct. 20, 1964, Precharged Fuel Injection Pump, now abandoned. The pump 11 does not have a so-called delivery valve and the reflected pressure waves from the nozzles 12, 13 are absorbed in the supply chamber 14 of the pump housing 16 since the nozzles are connected to the supply chamber by recess 17 and groove 18 in the plunger 19 during the time interval they are not being supplied injection pressure fuel via delivery port 21. The head of the pump housing 16 has a bore 22 in which plunger 1'9 reciprocates to pressurize fuel in pressure chamber 23 at the closed end of the Ibore and a plurality of delivery passages 24 adapted at the outer terminus for connection to injection conduits or lines 26. The pump 3,352,245 Patented Nov. 14, 1967 plunger is reciprocated by a cam 27 on a power take-off shaft 28 of a compression ignition engine 29 and is rotated by gears 31, 32. As the plunger is rotated, the distributor portion 33 of the plunger 19 cyclically connects the delivery passages to the delivery port and the supply chamber. A control sleeve 34 is provided to control the effective length of the pumping stroke and the timing of the fuel injection through axial shifting and rotating the sleeve by a suitable control member 36.

During operation,rthe supply pump 37 draws fuel from the source (reservoir) 38 by way of lter 39 and delivers it through conduit means, including branch conduits 41, by Way of lter 42 to injectors 12 and 13. Fuel passes downwardly through a central opening 43 in adjustable spring seat 44 and hence through passage 46 past a check valve 47, through passage 48 to cavity 49 by way of passage 51 in the differential pressure valve 52. It will be noted that the lower terminus of the passage 51 is adjacent the vale seat 53 and thus the ow of fuel through the cavity 49 will effectively cool the nozzle parts subjected to the highest temperatures. Fuel supplied the cavity 49 by supply pump 37 passes to the supply chamber 14 of the injection pump 11 via passage 54 in the nozzle 12, line 26 connected thereto, passage 24 in the injection pump 11, recess 17 and groove 18 in the plunger.

A pressure regulating valve 56 is provided in the pump housing 16 which opens at about 50 p.s.i. Fuel passing through valve 56 flows into the governor housing chamber 57 from whence it passes to the source 38 through return conduit 58.

Since the precharging recess 17 connects the delivery passages 24 to the supply chamber during the time they are not used for injection, the associated nozzles will be cooled by flow of fuel from supply pump 37. When pressurized fuel is delivered by the injection pump 11 to a nozzle, such as delivery to nozzle 13 as shown in FIGS. 1 and 2, the check valve therein will `close and the inwardly opening valve thereof will rise against its spring and fuel will -be injected into the associated engine cylinder.

In FIG. 3 I show a novel outwardly opening nozzle 61 which may be substituted for inwardly opening nozzles 12, 13. The supply line 41 of FIG. l would be connected to the upper end of passage 62 in the body 63 of nozzle 61 and the delivery line 26 of FIG. 1 would -be connected to passage 66 in body 63. The inner end of passage 62 terminates annular groove 72 at the cavity 67 in nozzle lbody 63. A resilient cylindrical diaphragm 71 covers the groove 72 and acts as a check valve during operation of the fuel injection system. The diaphragm deects inwardly to permit flow of fuel from the supply pump downwardly between the wall 70 of cavity 67 and the outer cylindrical surface of diaphragm 71 to cool valve element 69 and seat 68. When pressure wave of fuel delivered by the injection pump to passage 66 arrives at cavity 67 the diaphragm 71 is pressed against the wall 70 to close the recess 72. The radical clearance between the valve 69 and the wall 70, needed for flow of fuel and proper operation during injection, is utilized during cooling by the inwardly expanded diaphragm '71. This minimizes the diameter of the nozzle.

In FIG. 4 a thermostatic or temperature responsive valve 81 is installed in the pump housing 16. The spool 82 of valve 81 is shifted downwardly against the action of spring S3 to permit normal fuel flow and pressure relief, from supply chamber 14 to governor chamber 57 by way of annular recess 84 in spool `82 and passages 86, 87, by a bellows operated plunger 88 responding to sensor 89 disposed in the supply chamber 14. When the temperature of the nozzle 12 reaches a predetermined value the fuel passing therethrough will cause the temperature to rise in the supply chamber 14' and thus by choosing the correct thermostatic valve (or adjusting an adjustable version thereof) the normal supply pump flow will occur through the nozzles and supply chamber upon the temperature of the injector reaching a predetermined desired minimum temperature. Thereafter the cooling ow through the system will prevent excessive injector temperatures. When the thermostatic valve 81 is used, a pump relief valve 91 is required to prevent excessive pressure buildup during the interval of time that the valve 81 is in its closed position as illustrated. A bleed hole or passage 92 is provided in housing 16' to insure a small flow of -fuel even when the valve 81 is closed and thus the supply chamber will be vented of air or gases.

In FIG. 4 I also illustrate a novel means for providing cooling ow through the nozzles after engine shut down. An engine fuel shut off control 101 is connected to the fuel pump 11'` by suitable linkage 102 and when moved to its engine shut down (fuel shut oif) position it activates -a time control switch 103 through link 104. The switch 103 connects an electric motor 106 to the vehicle battery, not shown, and the motor 106 drives auxiliary pump 137 for a predetermined interval of time after engine shut down thus delivering fuel to conduits 41 connected, respectively, with a plurality of nozzles 12', only one of which is illustrated. It is possible to use a single supply pump 237 as shown in FIG. 5, with an overriding clutch 238 between the engine power take off shaft 239 and pump 237 and with an overriding clutch 241 between pump 237 and electric motor 211. As in the FIG. 1 embodiment of my invention, each injector 12 is connected to a delivery line 26 and the injection pump 11 is of the precharged type similar to pump 11. The automatic cooling of nozzles after engine `shut down `will prevent excessive heating (cooking) of the fuel in the cavity 49 of the .inwardly opening nozzle and cavity 67 of the outwardly opening nozzle. Cooking of the fuel may results in cracking of the fuel -and formation of carbon and tar deposits, which of course is quite detrimental to proper nozzle functioning.

My counter flow fuel injection system provides cooling of not only the injector nozzles butalso the pump head 90 and plunger 19. During operation there is flow of fuel from the supply pump through the delivery passages in the head and recess 17 and groove 18 in the plunger to provide continuous cooling of the pump head and plunger which yare subjectedto considerable heat due to compression of fuel in chamber 23, for instance as high as 10,000 p.s.i. peak pressure. There is continuous cooling of the pump head even during injection Since injection occurs through one delivery passage at a time while the other delivery passages are serving as cooling passages. Thus the mass of head 90 is continuously cooled to effectively prevent phenomena detrimental to the lling of pumping chamber 23 such `as vapor lock.

Cooling of the nozzles and pump head will not be necessary at low engine speeds and loads, however cooling is desired when engine load and speed increases. The temperature of the fuel supplied to the pump supply chamber via the nozzles will be `indicative of the temperature of the nozzles;lthereforethe nozzle temperature can be sensed in the supply chamber of the injection pump and the cooling ow governed accordingly.

Without any provision for nozzle cooling, the nozzle installation should be such as to result in tolerable temperatures at high engine yspeed and load. Therefore the temperatures at low engine speed and load may tend to be too low with an engine of high horsepower rating (for instance a turbocharged engine). This `may result in acid corrosion of injector parts if such an engine is subjected to long periods of idle operation. `Hence the advantage of my thermostatically controlled cooling flow.

The embodiments of the invention for which an exclusive property or privilege is claimed are dened .as follows:

1. A fuel injection system for a multicylinder engine, comprising:

a distributor type fuel injection pump having a supply chamber,

a high pressure chamber,

a bore opening into said high pressure chamber,

a plurality of delivery passages,

a reciprocating plunger in said bore for cyclically pressurizing fuel in `said high pressure chamber, and

means cyclically connecting said delivery passages one at a time to said high pressure chamber and connecting said delivery passages to said supply chamber when the latter are not connected to said high pressure chamber,

a fuel injection nozzle for each engine cylinder, each nozzle having a body with a pressure cavity,

a pressure responsive valve for delivering fuel from said pressure cavity to an engine cylinder associated with said nozzle, first and second branch passageways in said body connected to and extending from said cavity, and

check valve means insaid lirst passageway permitting flow therethrough in the direction toward said cavity and preventing ow in the opposite direction,

a fuel supply pump delivering fuel from a fuel source to said first passageways of said nozzles,

conduits connecting said second passageways of said nozzles to said delivery passages,-respec tively, and

conduit means connecting said supply chamber to said source.

2. The structure set forth in claim 1 and further cornprising a pressure regulating valve in said conduit means connecting said supply chamber to said source for maintaining the pressure of fuel in said supply chamber at an intermediate pressure above atmospheric pressure and substantially below injection pressure.

3. The structure se-t for-th in claim 1 wherein said pres-r sure responsive valves of said nozzles are outwardly opening valves.

4. The structure set forth in claim 3 wherein said check valve means includes a flexible diaphragm covering the terminus of said rst passageway at said cavity.

5. The structure set forth in claim 1 and further comprising ilow control means for preventing normal flow of fuel from said supply chamber to said source until the temperature of fuel returning from said nozzles exceeds a predetermined minimum.

6. The structure set forth in claim 5 wherein said flow control means includes a temperature responsive valve in said conduit means connecting said supply chamber to said source.

7. The structure set forth in claim 6 wherein said ow control means includes a bleed passage permitting limited ow from said supply chamber to said source when said temperature is below said predetermined minimum.

8. The structure set forth in claim 6 and further comprising a pressure relief valve for connecting the outlet of said pump to the inlet of said pump when the pressure exceeds a predetermined value.

9. The structure set forth in claim 6 wherein said flow control means includes a temperature sensor disposed in part in saidlsupply chamber and operatively connected in actuating relation to said temperature responsive valve.

10. In an injection system for a multiple cylinder en- 7 gine, the combination comprising:

a plurality of fuel nozzles for injecting fuel into each said cylinder,

a pressure operated valve in each of Said nozzles for controlling flow of fuel from said nozzles to said engine cylinders,

an engine driven fuel supply pump for continuously pumping fuel directly through the bodies of each of said nozzles,

conduit means connecting said supply pump t-o said nozzles whereby said nozzles are connected in parallel,

an engine driven distributor type fuel injection pump for cyclically delivering high pressure fuel to said nozzles by Way of a plurality of fuel delivery passages, and

a plurality of conduits connecting said nozzles to said delivery passages, respectively, lsaid conduits and injection pump normally forming unobstructed path- Ways permitting fuel to flo-W to said nozzles from said injection pump during injection periods and from said nozzles -to said injection pump during noninjection periods.

11. The structure set forth in claim and further ycomprising pump means for automatically pumping fuel through said nozzles to cool the same for a predetermined time interval upon engine shutdown.

12. The structure set forth in claim 11 and further comprising check valve means at each of said nozzles preventing flow from said nozzle to said supply pump by Way of said conduit means.

13. The structure set for-th in claim 12 and further comprising pressure regulating means causing the pres sure in said conduits to be substantially above atmospheric pressure and substantially below injection pressure during noninjection intervals.

14. The structure set forth in claim 12 wherein said 5 nozzle is ofthe outward opening type.

15'. The structure set forth in claim 12 and fur-ther comprising temperature lrespo-nsive valve means for substantially preventing flow from said nozzles through said conduits when said fuel in said nozzles is below a prede- 10 termined temperature and pressure relief means for said supply pump.

References Cited UNITED STATES PATENTS ROBERT A. OLEARY, Primm Examiner.

W. I. KRAUSS, Assistant Examiner. 

1. A FUEL INJECTION SYSTEM FOR A MULTICYLINDER ENGINE COMPRISING: A DISTRIBUTOR TYPE FUEL INJECTION PUMP HAVING A SUPPLY CHAMBER, A HIGH PRESSURE CHAMBER, A BORE OPENING INTO SAID HIGH PRESSURE CHAMBER, A PLURALITY OF DELIVERY PASSAGES, A RECIPROCATING PLUNGER IN SAID BORE FOR CYCLICALLY PRESSURIZING FUEL IN SAID HIGH PRESSURE CHAMBER, AND MEANS CYCLICALLY CONNECTING SAID DELIVERY PASSAGES ONE AT A TIME TO SAID HIGH PRESSURE CHAMBER AND CONNECTING SAID DELIVERY PASSAGES TO SAID SUPPLY CHAMBER WHEN THE LATTER ARE NOT CONNECTED TO SAID HIGH PRESSURE CHAMBER, A FUEL INJECTION NOZZLE FOR EACH ENGINE CYLINDER, EACH NOZZLE HAVING A BODY WITH A PRESSURE CAVITY, A PRESSURE RESPONSIVE VALVE FOR DELIVERING FUEL FROM SAID PRESSURE CAVITY TO AN ENGINE CYLINDER ASSOCIATED WITH SAID NOZZLE, FIRST AND SECOND BRANCH PASSAGEWAYS IN SAID BODY CONNECTED TO AND EXTENDING FROM SAID CAVITY, AND 